Brief information about starfish. Jellyfish, corals, polyps

A living starfish is a real decoration not only of the ocean floor, but also of the aquarium, however, in order for it to please the eye for many years, you need to know about all the conditions of its maintenance.

Starfish in natural conditions

Many ichthyologists claim that this animal appeared about 450 million years ago. How true this statement is is unknown, but one thing is clear: this predator plays a significant role in the harmony and beauty of the underwater depths. Nowadays, such a “decoration” is welcome not only at the bottom of the sea, but also in, where it also looks great against the background of other inhabitants.

Even a novice amateur knows what a starfish looks like, so he is unlikely to confuse it with another inhabitant. True, in order for your pet to live well in an artificially created underwater kingdom, you need to take into account a number of features of its maintenance.

Beginning hobbyists should first acquire an unpretentious species, since more complex varieties, due to the owner’s lack of maintenance experience, may wither or die. Sometimes, together with “living” stones, a small asterine can get into the home sea, which gets along well with other inhabitants and feeds on the algae fouling on the glass. It is not worth removing it, since it does not cause any harm, but it can create a spectacle when it crawls onto the glass.

Structure of a starfish

Of great interest is the structure of the animal, which belongs to the class

Structure

invertebrates and the phylum echinoderms. It is thanks to its multi-rayed body shape that it got its name. At the bottom of the sea there live a huge number of species, which are characterized not by a multi-rayed, but by a pentagonal and five-rayed body shape.

These invertebrates boast a solid calcareous skeleton, which consists of individual plates movably connected to each other, as well as a well-developed ambulacral system, which is a whole network of channels filled with liquid. Skeletal appendages in the form of spines, tubercles and needles located on the surface serve as a kind of “protection”. For cleaning skin the animal uses special grasping organs called pedicellariae. Predators use them to remove dirt and pieces of algae from their bodies, like tweezers. The mouth is located in the center of the disc, on the lower (ventral) side.

If you look at more than one description of these echinoderms, you will find out that most of them are predators. Such individuals feed on other small invertebrate creatures by attaching their legs to them. In this case, the prey is eaten on the spot, since the invertebrate predator, having attached itself, simply turns out its pouch-like stomach and envelops the prey with it.

Reproduction and compatibility of starfish

Red starfish in an aquarium

Not all are mysterious creatures ocean depths they know how to survive in an artificially created “sea”, but the starfish in the aquarium takes root well. However, it is contraindicated to place animals in a body of water inhabited only, since they are very sensitive to the products of their vital activity. In addition, they will be undesirable neighbors for various invertebrate mollusks.

This is especially true since “five-pointed predators” can simply eat them. In a home pond, they can not only attack an animal, but also bite off its rays, and even eat it.

The reproduction of starfish deserves special attention, since they can do this in several ways. For the most part, these animals are divided into females and males, who, to prolong their race, spawn eggs and sperm directly into the water.

After their fertilization, free-swimming larvae can be seen in the water column. At first, a cluster of larvae is observed around the adult individual, and under the influence of its pheromones, after a few weeks, the babies undergo metamorphosis and are already attached to the bottom in the form of tiny five-linked organisms.

And hermaphrodite individuals bear larvae either near the mouth or on the back in special cavities. The last method of reproduction is that the adult discards one of the limbs, which quickly regenerates and, as a result, four missing ones grow from one ray. In ancient times, shrimp catchers tried to reduce the population of these predatory invertebrates by tearing them into pieces, but by doing so they only increased their number on the seabed, harming the shrimp even more.

Feeding

As mentioned above, these organisms cannot be placed in the same body of water with shrimp, sponges and bivalves because of taste preferences first. A novice hobbyist must know what these amazing organisms feed on, because improper feeding will quickly affect their condition.

In a home pond, many species have enough fouling of living stones, artificial driftwood and the walls of a “transparent house”, but you can also give pieces of shellfish and shrimp meat, as well as various food for bottom inhabitants.

Feeding should be done once a day and feed should be used as much as the body can eat in one sitting. Otherwise, food residues will accumulate at the bottom, which will begin to decompose and negatively affect the quality of the water.

Are starfish dangerous for humans?

Despite the fact that many echinoderms look quite menacing, bearing spines and having a “warning” coloration, they are completely safe for humans. They do not bite, shock or attack a person swimming in the sea.

True, there is poisonous species, or rather, one species called Crown of Thorns (Acanthaster planci). The body of this organism is covered a large number sharp thorns that resemble thorns.

The bases of the needles are equipped with poisonous glands, which cause serious poisoning in humans and other sea inhabitants when pricked. They live on coral reefs, which serve as the main food for “prickly” predators.

As for size, this class is represented by creatures ranging in size from a few millimeters to more than a meter. For example, the largest specimen raised from the bottom of the Gulf of Mexico reaches a length of 1.38 meters from one end to the other. This is a fragile brisingid (Midgardia xandaros).

Variety of species

Such deep-seated inhabitants as look great and get along in the same aquarium with the stars. But you shouldn’t house big ones with them. predatory fish, crustaceans and other echinoderms, which can become enemies for them.

Care is not difficult, since the animals clean themselves, find food on stones and walls of the reservoir, and also move little. The colors of the animals are striking in abundance color range and brightness, so against the background of green algae and gray stones they look almost fantastic. And although animals lead a bottom-dwelling lifestyle, this does not prevent them from creating a surprisingly spectacular effect in their home pond.

It is not for nothing that red sea starfish are very popular among amateurs, because they are not only beautiful, but also not particularly pretentious. Particularly often bought are varieties such as

(Linkia laevigate), Red Linkia (Linkia multiflora), Red Phromia (Fromia milleperella) and others.

Content Features

You should not get capricious species of echinoderms from the very beginning, since sometimes the slightest mistake can lead not only to illness of the pet, but also to its death. Although these creatures do not have blood, they can also get sick because water passes through their bodies. This means that the state of the “five-pointed” friend may well depend on the state of the water in your system. Therefore, enough time must then pass before introducing these delicate organisms into it to be sure that the quality of the water will be at the proper level. It is also worth remembering that the reservoir should be spacious, despite the fact that not very mobile inhabitants will live there.

Not all home sea lovers know how starfish move, so due to ignorance, you can make a number of mistakes when choosing soil.

Among other things, a beginner needs to know what these organisms eat, because they are not always suitable for these animals. Various deep foods are suitable for their nutrition, but echinoderms do not disdain the meat of shrimp and shellfish, because in nature these invertebrates are their favorite food. It is possible that the animal will gorge itself on fouling alone, so you cannot sprinkle a lot of food. She will definitely not remain hungry, but as for water, if she is fed heavily, it will need to be replaced as soon as possible.

In general, keeping echinoderms at home is not particularly difficult, but like any other living organism, it will not tolerate neglect. Therefore, before getting this animal, you need to be sure of your knowledge and desire. Only when proper care the mysterious inhabitant of the ocean depths will delight the eye of its owner and arouse admiration among other people.

Starfish are veterans of the seabed, they appeared more than 450 million years ago, ahead of many forms of modern inhabitants of the underwater depths. They belong to the class Echinodermata, being relatives sea ​​cucumbers, brittle stars, sea lilies, sea cucumbers, sea urchins - currently there are about 1,600 species with a star-shaped or pentagonal shape.

The starfish, despite its inactivity and the absence of a head as such, has a well-developed nervous and digestive system. Why, exactly, “echinoderms”? It's all about the hard skin of the starfish - on the outside it is covered with short needles or spines. Conventionally, these bizarre creatures can be divided into three groups: ordinary starfish; feather stars, named for their writhing rays (up to 50!), and “fragile” stars that cast off their rays in case of danger.

True, it will not be difficult for this animal to grow new ones, and new stars will soon appear from each ray. How is this possible? - Thanks to characteristic feature structure of the star - each of its rays is structured identically, and contains: two digestive outgrowths of the stomach, performing the function of the liver, a red eyespot at the tip of the ray, protected by a ring of needles, radial bundles of nerves, olfactory organs (they are also suckers and a method of movement), located in a groove on on the ventral side of the papules - skin gills in the form of thin short villi, located on the back and producing gas exchange processes of the genital organs (usually two gonads on each ray); a skeleton consisting of a longitudinal row of vertebrae inside, and hundreds of calcareous plates with spines covering the skin and connected muscles, which not only protects the animal from damage, but also makes its rays very flexible. The bodies of starfish are 80% calcium carbonate.

Thus, each ray of a starfish, once separated from its body, is completely viable and quickly regenerates. Well, connected together, the rays form closed systems in the center of the animal: digestive system passes into the stomach from two sections and opens with a button-shaped disc that serves as the mouth; bundles of nerves unite into a nerve ring. The main system of the starfish, which we deliberately left “for dessert,” is the ambulacral system. This is the name given to the water-vascular system, which serves the echinoderm simultaneously for respiration, excretion, touch and movement, together with the muscles providing musculoskeletal function. Canals extend from the perioral ring into each ray, from them, in turn, lateral branches to hundreds of cylindrical tubes on the surface of the body - ambulacral legs containing special ampoules and ending with suction cups. An opening on the back, called the mandreoporous plate, serves to connect this system to the external aquatic environment.

So how does the ambulacral system work? - It is filled with water under slight pressure, which, entering through the mandreoporous plate into the perioral canal, is divided into five ray channels and fills the ampoules at the base of the legs. Their compression, in turn, fills the legs with water and stretches them. In this case, the suckers of the legs attach to various objects of the seabed, and then sharply contract, the ambulacral legs are shortened, and thus the body of the animal moves in smooth jerks.

Starfish are voracious predators, although there are exceptions in the form of herbivorous species that feed on algae and plankton. In general, the favorite delicacies of these animals are clams, mussels, oysters, scallops, littorinas, barnacles, reef-building corals and various invertebrates. The star finds prey by smell. Having discovered a mollusk, it attaches itself with two rays to one shell valve, and the remaining three to the other valve, and a multi-hour struggle begins, which the starfish always wins. When the mollusk gets tired and the doors of its home become pliable, the predator opens them and literally throws its stomach on the victim, turning it out! By the way, food digestion occurs outside the animal’s body. Some starfish are even capable of digging out prey hiding in the sand.

As for reproduction, most starfish are divided into males and females. Fertilization occurs in water, after which free-swimming larvae called brachiolaria are formed. Unlike adult individuals, their structure is subject to the laws of symmetry, and includes a ciliary cord necessary for collecting food particles (exclusively unicellular planktonic algae), a stomach, esophagus and hind intestine. Usually the larvae swim near an adult sea star of the same species - and after several weeks, under the influence of its pheromones, they undergo metamorphosis: having fixed themselves on the bottom, they turn into tiny (0.5 mm in diameter), but already five-linked starfish. But these babies will be able to give birth only after two or three years. If the larvae perform the function of dispersing species, and drift over long distances, they are able to delay their transformation into adults and not settle to the bottom for several months - and they can grow up to nine cm in length. Among the starfish there are also hermaphrodites - they carry their young in a special brood pouch or cavities on the back.

Taking into account the large number of sea stars, it is clear that they also influence the growth of populations of the species that are hunted. Nobody risks hunting them, since their bodies contain extremely toxic substances- asteriosaponins. Being virtually invulnerable, starfish are at the top of the marine food pyramid and can therefore have a lifespan of up to 30 years. If you believe scientists, then these brightly colored legendary inhabitants of the seas also make a significant contribution to the process of recycling carbon dioxide, including those produced by industrial facilities on the planet - their share is about 2% of CO2, that is, more than 0.1 gigatons of carbon per year, which, you see, is not weak at all for such seemingly small creatures!

What do you know about starfish? Beautiful and unusual creatures, with many interesting facts from their life - in our selection. Currently, about two thousand species of starfish are known.

Starfish have no brain or blood - to obtain nutrients, oxygen and other important fluids, the starfish pumps through its body sea ​​water. It is the resulting water that is distributed throughout the body and forms the “water-vascular system.”

On each arm of a starfish, mistaken for tentacles, there are about 15 thousand tiny suckers that help the starfish move.

A starfish is not a fish, but an invertebrate animal.
Starfish are true predators. They are capable of attacking their own kind and can easily feast on the small offspring of their own species, i.e. are cannibals.

Stars have two stomachs, one of which they can even push out to digest shellfish.

Starfish are long-lived, some species live up to 30-35 years.

Many of the starfish are very dangerous. For example, the crown-of-thorns starfish, which is distributed throughout the Indo-Pacific Ocean, is covered in venomous spines. Growing to almost half a meter in length, these creatures become dangerous not only for coral reefs, but also for divers and swimmers.

Starfish can easily change gender and then switch back. True, for such “transformations” several suitable conditions are needed - water quality, temperature and food availability.

Starfish have eyes - exactly as many as there are rays; at the tip of the rays there is an eye, which looks like a red spot. They don’t see very well, of course, but at least they can distinguish between darkness and light.

Even though starfish live underwater, they do not have gills.

Although the appearance of most starfish corresponds to their name, sometimes unusual individuals with bizarre shapes are found. For example, starfish may have a sun-shaped shape, multiple rays, or their shape may be rounded.

The heart of starfish beats at a frequency of 5-7 beats per minute.

The largest starfish can reach 1 meter in diameter and their weight can reach 5 kilograms. solar stars more active than their relatives, and are able to quickly pursue their prey, and, having incredible strength, simply tear the shell of mollusks and crustaceans.

Feeding method that allows starfish to eat prey much larger than the mouth opening looks like this - since the starfish’s mouth is on the underside of its body, the star, having grabbed the prey, wraps its strong hands around it, and then with a strong push he places it under himself, and then pushes it into the stomach.

They are also some of the most ancient inhabitants of the Earth. Starfish are about 250 million years old.

Stars move using hundreds of tubes that are attached to the surface and then move in waves.

Starfish live at various depths, up to ten kilometers

In the last few years, starfish have begun to actively reproduce. This creates a problem, because each individual has an excessive appetite and consumes about 6 square meters corals per year. In some areas, measures are being taken to destroy stars.

However, starfish still bring much more useful than harmful - they are important consumers of carbon dioxide - every year sea stars in total destroy about 2% of the Earth's carbon dioxide, and this is extremely big number within the entire planet.

Another useful role of starfish is to clean the seabed of carrion, weak and sick creatures of the seabed, as well as the remains of dead oceanic organisms.

Starfish go through five stages of growth before becoming adults - during the first month, stars are free-swimming and jellyfish-like, they are small, almost invisible to the eye and tiny plants and animals of the ocean.

Although most starfish are not poisonous, a large star called acanthaster or crown of thorns– dangerous for humans. The pricks of its needles bring burning pain to a person - if the needle gets stuck in the skin, then it breaks off from the star’s body and begins to infect the person’s blood with poisonous secretions.

An interesting fact is that if you cut off one of the arms of a starfish or all of them at once, without damaging the central part of the body, they will gradually grow back.

Starfish and their relatives are called echinoderms. Many representatives of this group are indeed extremely prickly. These creatures, quite numerous and widespread, live in the sea, and for this reason many of them are not well studied. Unlike most animals, the body of echinoderms has radial symmetry. Another feature of echinoderms: small hydraulic (fluid-filled) legs ending in a suction cup. Most groups of marine animals include several species adapted to life in fresh water or on land. There are none among echinoderms. These creatures are relatively large in size, many are brightly colored, and are usually easy to see because they move slowly.
The body of starfish is flattened and equipped with the semblance of arms, which radiate in rays from the center of the animal’s body.
Usually the number of rays of starfish is 5, but there are species with 7 and even 14 rays. Upper part The animal's body usually bears small, hard protective plates or spines located in the skin. On the underside, each ray is equipped with rows of tiny tube feet, like miniature fingers with suction cups at the ends. The rays are able to bend, allowing starfish to glide easily along the seabed. Starfish have sufficient strength to open shells. Starfish presses a pair of rays to each side of the shell. Then, with great strength and no less patience, she begins to unclench the doors. As soon as a small gap appears between them, the starfish immediately pushes its stomach, turned outward through its mouth, into it. From this moment on, the predator begins to digest the flesh of the prey. Soon the shell finally opens and the starfish finishes its meal.

Red starfish (Asterias rubens) very numerous in the White Sea. Sometimes they move slowly along the seabed in huge schools covering an area of ​​2.5 square km, feeding on bivalves, worms, crabs, and other echinoderms. Stars of the genus Astropectens prefer a sandy seabed, into which they submerge halfway. Five rays of this beautiful star equipped with spikes. The fourteen rays of the fairly common solar starfish are bright red and resemble the rays around the sun's disk. She even hunts other starfish.
Brittle stars, or snaketails, - the fastest and most active among echinoderms. Their "arms" are very flexible, and brittle stars can walk by bending them. Moving on your “hands” is much faster than using hydraulic legs. Most brittle stars live below the tidal zone, in deep water. Sometimes they are found in clusters of up to 1000 individuals on an area of ​​​​the seabed of several square meters. Most brittle stars feed by collecting small edible food particles in the mud or filtering them from the water. Species living in the Atlantic and Mediterranean regions are filtrate feeders. They live in a dense colony, where each individual strives to grab all edible food particles floating by with its spiky rays.
sea ​​lilies They were once very numerous, but now they are much smaller. Like all echinoderms, they are equipped with feathery arms-rays, which they use for feeding and movement. Many have up to ten rays, but there are species whose number of rays reaches 200! Sea lilies lead a life attached to rocks, but some can also crawl. These animals feed by filtering food particles from the water with their developing rays. The most ancient sea lilies are attached to the bottom with a stalk.

If starfish damaged or lost part of the “arm”, she is able to regenerate this lost part. The reconstructed limb is usually slightly smaller. Sometimes it splits into two branches, resulting in a starfish with six arms!
Crown of thorns starfish feeding. Sometimes they multiply so much that they completely eat coral reef. They do not have many natural enemies: they are covered with sharp poisonous thorns.
The Pacific sea star Linkia moves very slowly, which, however, does not prevent it from being a successful predator.
Starfish don't look like anything, but they are all ferocious predators.

Echinoderms:
- 6250 species
- Sea life
- Five-ray symmetry
- Internal skeleton, the spines often stick out
- Tiny tube feet

Main classes:

1. Starfish
- 1500 types
- Usually 5 rays (sometimes more)

2. Brittle stars
- 2000 species
- Flattened and star-shaped
- Usually 5 rays (sometimes 6 or branched rays)
- The rays are long, fragile and flexible

3. sea ​​lilies
- 625 species (mostly stemless)
- There are floating (stemless) and sessile (stalked) forms
- They feed by filtering water

If you find yourself in the Dominican Republic, do not miss the chance to visit the Blue Lagoon and get acquainted with its beautiful and unusual inhabitants - starfish. You will find shocking facts about these creatures in this article!

Starfish are not just beautiful decorations and decoration of the seabed. At first glance, they seem primitive and somehow unreal. But appearances are deceiving. These animals have a complex nervous and digestive system.

Well, for example: did you know that the starfish is a real predator? And stars can move along the seabed over considerable distances. And this is not all that is known about starfish.

Facts about starfish

We have collected for you the most interesting facts about these amazing animals.

According to the texture of the body surface, starfish are:

• smooth
• spiky
• prickly
• rough
• velvety
• mosaic
• plain and patterned
• bright and faded

Starfish come in a wide variety of colors. Most often this

• different shades of red
• blue
• brown
• pink
• violet
• yellow
• black

The deeper the sea star's habitat, the paler it is. Those individuals that live in shallow waters are distinguished by the brightest colors.

Food and hunting

Starfish have a kind of sense of smell - they are able to detect chemicals. This helps them hunt.

Yes, yes - most starfish are real predators!

Here are just some of the inhabitants of the seabed that the stars hunt:

• shellfish
• crustaceans
• plankton
• sponges
• corals
• gastropods
• other invertebrates, including echinoderms. For example, sea urchins are one of the starfish’s favorite delicacies.

The process of hunting, absorption and subsequent digestion of prey requires a separate story. We advise the faint-hearted and impressionable to scroll through these details.

The starfish is not picky about food and eats everything it can digest. She does not disdain carrion.

On the abdomen of the starfish there is a mouth through which it absorbs prey. If any mollusk becomes its victim, then the starfish crawls onto it and sticks its rays to its valves. Thanks to the adhesive lubricant, the star manages to stick very firmly to the shells of the mollusk.

After this it starts long struggle: the mollusk compresses the valves of its shell, protecting itself from a predator, and the star strives to open them to gain access to the contents.
As a rule, the outcome of this confrontation is disastrous for the mollusk: the starfish is much stronger. And besides, for hearty lunch a gap of only 0.1 mm is enough for her!

Then something fantastic happens: the starfish turns out its stomach, which can stretch up to 10 centimeters! The stomach penetrates the shell of the mollusk, where the entire digestive process takes place, lasting several hours.

Thanks to its expandable stomach, the starfish can even digest prey that is significantly larger than its size. There is a known case where a starfish died after swallowing such a large sea ​​urchin that she could not spit out the remains of it.

Reproduction

Starfish reproduce in different ways:

• Reproduction by regenerative means.

Due to softening connective tissue the starfish breaks up into several parts or casts off its rays. Then full-fledged stars grow from these parts.

• Sexual reproduction.

In a starfish, the gonads are located in pairs at the base of each ray. During mating, males and females connect their rays and release sperm and eggs into the water.

Those species of starfish that bear offspring lay 200 or more eggs.

Female starfish, whose larvae are free-swimming, are capable of laying up to 200 million eggs!

Among starfish there are also unisexual species. The bodies of such stars produce both male and female reproductive products. They carry their offspring in a brood pouch or special holes on their back.

And there are also species that during their lives change sex from male to female (for example, the asterine starfish).

There are three types of starfish larvae:

• in one type of star, the egg hatches into a larva that swims freely and feeds on tiny pieces of algae. After a few weeks, it attaches to the bottom and gradually turns into a small star with a diameter of 5 centimeters.
• in another type, the larva has large reserves of yolk, which allows it to do without additional nutrition and grow into an adult star
• in those stars that live in cold waters, the larvae remain on the mother’s body and concentrate around her mouth. Therefore, during this period, the female has to do without food and move very, very carefully, arching her body so as not to harm the larvae.

The size of the larvae usually does not exceed 3-5 mm

Starfish larvae can be carried by currents over enormous distances.

The starfish becomes sexually mature only at the age of 2-3 years.

The starfish is almost invulnerable. From natural enemies she is protected:

• sharp thorns (sometimes poisonous)
• ability to bury itself in sand in case of danger

• shrimps
• shellfish
• polychaete worms

They settle on the back of the starfish and cause damage to its covering. The star herself tries by all means to get rid of uninvited guests.

Benefits for the eco system

Starfish have a positive effect on the ecology of the oceans and the planet as a whole:

• absorb and utilize harmful to the planet carbon dioxide, which is becoming more and more abundant in the Earth’s atmosphere every year
• are orderlies of the seabed, eating carrion and the remains of the dead marine organisms, as well as weaker and sicker individuals of marine animals

Some of the brightest and most beautiful representatives of this species live near the southern coast Dominican Republic. You can get to know them by visiting the Blue Lagoon. A visit to this natural pool located right in the middle of Caribbean Sea, included in all excursions to Saona Island.

The Blue Lagoon, as well as the islands of Saona, Catalina and Catlinita are part of the Eastern National Nature Reserve. And all the nature in these territories is carefully protected.

The lives of starfish are also protected. In order to preserve the population of this species, as of October 2017, starfish are prohibited from being taken out of the water. And yet, starfish, as before, decorate the bottom of the water area and no one will stop you from admiring them.

Let's take care of nature and the fragile lives of starfish!
And then everyone will be pleased to return to the Blue Lagoon again and again to visit their old star acquaintances.